soul网关源码解析-http长轮询(soul-admin)

我们看下soul-admin的类
ConfigController

public class ConfigController {

    @Resource
    private HttpLongPollingDataChangedListener longPollingListener;

    /**
     * Fetch configs soul result.
     *
     * @param groupKeys the group keys
     * @return the soul result
     */
     //获取数据
    @GetMapping("/fetch")
    public SoulAdminResult fetchConfigs(@NotNull final String[] groupKeys) {
        Map<String, ConfigData<?>> result = Maps.newHashMap();
        for (String groupKey : groupKeys) {
            ConfigData<?> data = longPollingListener.fetchConfig(ConfigGroupEnum.valueOf(groupKey));
            result.put(groupKey, data);
        }
        return SoulAdminResult.success(SoulResultMessage.SUCCESS, result);
    }

    /**
     * Listener.
     *
     * @param request  the request
     * @param response the response
     */
	//监听
    @PostMapping(value = "/listener")
    public void listener(final HttpServletRequest request, final HttpServletResponse response) {
        longPollingListener.doLongPolling(request, response);
    }

我们先看下方法fetchConfig

 public ConfigData<?> fetchConfig(final ConfigGroupEnum groupKey) {
        ConfigDataCache config = CACHE.get(groupKey.name());
        switch (groupKey) {
            case APP_AUTH:
                List<AppAuthData> appAuthList = GsonUtils.getGson().fromJson(config.getJson(), new TypeToken<List<AppAuthData>>() {
                }.getType());
                return new ConfigData<>(config.getMd5(), config.getLastModifyTime(), appAuthList);
            case PLUGIN:
                List<PluginData> pluginList = GsonUtils.getGson().fromJson(config.getJson(), new TypeToken<List<PluginData>>() {
                }.getType());
                return new ConfigData<>(config.getMd5(), config.getLastModifyTime(), pluginList);
            case RULE:
                List<RuleData> ruleList = GsonUtils.getGson().fromJson(config.getJson(), new TypeToken<List<RuleData>>() {
                }.getType());
                return new ConfigData<>(config.getMd5(), config.getLastModifyTime(), ruleList);
            case SELECTOR:
                List<SelectorData> selectorList = GsonUtils.getGson().fromJson(config.getJson(), new TypeToken<List<SelectorData>>() {
                }.getType());
                return new ConfigData<>(config.getMd5(), config.getLastModifyTime(), selectorList);
            case META_DATA:
                List<MetaData> metaList = GsonUtils.getGson().fromJson(config.getJson(), new TypeToken<List<MetaData>>() {
                }.getType());
                return new ConfigData<>(config.getMd5(), config.getLastModifyTime(), metaList);
            default:
                throw new IllegalStateException("Unexpected groupKey: " + groupKey);
        }

从这里我们可以看出这里是从实际上在获取数据的时候从本地缓存中获取数据然后再根据类型返回具体的数据.
再看下具体的方法

  public void doLongPolling(final HttpServletRequest request, final HttpServletResponse response) {

        // compare group md5 把有变动的数据返回
        List<ConfigGroupEnum> changedGroup = compareChangedGroup(request);
        //获取IP
        String clientIp = getRemoteIp(request);

        // response immediately. 不为空的话返回数据
        if (CollectionUtils.isNotEmpty(changedGroup)) {
            this.generateResponse(response, changedGroup);
            log.info("send response with the changed group, ip={}, group={}", clientIp, changedGroup);
            return;
        }

        // listen for configuration changed.
        final AsyncContext asyncContext = request.startAsync();

        // AsyncContext.settimeout() does not timeout properly, so you have to control it yourself
        asyncContext.setTimeout(0L);

        // block client's thread.
        scheduler.execute(new LongPollingClient(asyncContext, clientIp, HttpConstants.SERVER_MAX_HOLD_TIMEOUT));
    }

检查数据是否有变动的方法.

   private List<ConfigGroupEnum> compareChangedGroup(final HttpServletRequest request) {
        List<ConfigGroupEnum> changedGroup = new ArrayList<>(4);
        //循环每种类型的数据
        for (ConfigGroupEnum group : ConfigGroupEnum.values()) {
            // md5,lastModifyTime
            String[] params = StringUtils.split(request.getParameter(group.name()), ',');
            if (params == null || params.length != 2) {
                throw new SoulException("group param invalid:" + request.getParameter(group.name()));
            }
            String clientMd5 = params[0];
            long clientModifyTime = NumberUtils.toLong(params[1]);
            ConfigDataCache serverCache = CACHE.get(group.name());
            // do check. 检查是否有变动,变动添加list中
            if (this.checkCacheDelayAndUpdate(serverCache, clientMd5, clientModifyTime)) {
                changedGroup.add(group);
            }
        }
        return changedGroup;
    }

返回数据的方法

    private void generateResponse(final HttpServletResponse response, final List<ConfigGroupEnum> changedGroups) {
        try {
            response.setHeader("Pragma", "no-cache");
            response.setDateHeader("Expires", 0);
            response.setHeader("Cache-Control", "no-cache,no-store");
            response.setContentType(MediaType.APPLICATION_JSON_VALUE);
            response.setStatus(HttpServletResponse.SC_OK);
            response.getWriter().println(GsonUtils.getInstance().toJson(SoulAdminResult.success(SoulResultMessage.SUCCESS, changedGroups)));
        } catch (IOException ex) {
            log.error("Sending response failed.", ex);
        }
    }